Liquid crystal display devices are commonly used as display devices for compact electronic apparatuses, because they not only are very thin but also provide good quality images with little power consumption.
FIG. 9 shows an exploded, isometric view of a typical LCD device 1. The LCD device 1 includes a bezel 10, a liquid crystal panel 20, and a backlight module 40 disposed adjacent to the liquid crystal panel 20.
The bezel 10 includes a generally rectangular top plate 102, and four first side walls 104 extending downward from four edges of the top plate 102. The top plate 102 defines an essentially rectangular display region 107 thereof. Each first side wall 104 defines two first notches 106 therein.
The backlight module 40 includes a brightness enhancement film (BEF) 422, a diffusion film 421, a light guide plate (LGP) 430, an illuminator 440, a reflection film 460, a frame 450, and a bottom tray 470. The frame 450, the BEF 422, the diffusion film 460, the LGP 430, and the reflection film 460 are arranged in that order from top to bottom.
The LGP 430 includes a top light incident surface 433, a light emitting surface 431 adjoining the light incident surface 433, and a bottom surface 432 adjoining the light incident surface 433. The illuminator 440 is positioned opposite the light incident surface 433.
The frame 450 includes four second side walls 452 arranged end to end, and a supporting board 454. Each second side wall 452 includes two first protrusions 456 and two second protrusions 457 integrally extending perpendicularly outwardly from an outer surface (not labeled) thereof. The supporting board 454 has a frame shape, and integrally extends perpendicularly inward from inner surfaces (not labeled) of the second side walls 452. The frame 450 therefore defines an upper space for accommodating the liquid crystal panel 20, and a lower space for accommodating the BEF 422, the diffusion film 421, the LGP 430 and the reflection film 460. The first protrusions 456 correspond in position to the first notches 106.
The bottom tray 470 includes a bottom wall 472 and eight side plates 474. The side plates 474 extend perpendicularly upward from four sides of the bottom wall 472. Two side plates 474 are located at each of four corners of the bottom tray 470, respectively. Each side plate 474 defines a second notch 476, corresponding to one of the second protrusions 457 of a respective second side wall 452 of the frame 450.
When the LCD device 1 is assembled, the BEF 422, the diffusion film 421, the LGP 430, and the reflection film 460 are received in the lower space. The second protrusions 457 of the second side walls 452 of the frame 450 are engagingly received in the second notches 476 of the bottom tray 470. Thereby, the frame 450 and the bottom tray 470 are locked together. The liquid crystal panel 20 is received in the upper space. The first protrusions 456 are engagingly received in the first notches 106, and the frame 450 and the bezel 10 are thereby locked together.
When the LCD device 1 is assembled, this is typically performed manually by a human operator. The bottom tray 470 and the frame 450 are generally locked together by force applied in four different directions corresponding to the four second side walls 452. The bezel 10 and the frame 450 are generally locked together by force applied in four different directions corresponding to the four second side walls 452. Thus assembly or disassembly of the LCD device 1 is somewhat complicated, problematic, and time-consuming. In addition, a size of each first protrusion 456 is usually slightly less than a size of each corresponding first notch 106, in order to facilitate assembly. However, this may result in loose engagement of the first protrusions 456 in the first notches 106. Similarly, a size of each second protrusion 457 is usually slightly less than a size of each corresponding second notch 476, in order to facilitate assembly. However, this may result in loose engagement of the second protrusions 457 in the second notches 476.
What is needed, therefore, is a backlight module and a liquid crystal display device using the backlight module that can overcome the above-described deficiencies.